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Abdomen:Solid viscus:Testis (note: ovary is classified in pelvis)
The testes are the male genital organs, and are contained within a sac called the scrotum. The testes are responsible for production of sperm and testosterone. At birth, testes measures approximately 1.5 cm (length) x 1 cm (width), reaching 4 cc at puberty. Normal adult testes is ovoid and measures approx 3 cm (AP) x 2.5 cm (TR) x 5 cm (length), with a volume of 12.5-19 cc. The size of the testes decreases with age. The testes is covered by thick fibrous tissue called the tunica albuginea. The epididymis is attached to its posterolateral surface. The vas deferens arise from the lower pole of the epididymis, run up medial to it behind the testis. The front and sides of the testis lie in a serous spaces formed by the tunica vaginalis. * The proximal pole of the epididymis is attached to the mediastinum testis, from which several radiating septae extend into the testis forming 250-400 lobules. * Each of these lobules contain 1-4 seminiferous tubules. These tubules carry the sperm via tubuli recti into a dilated space within mediastinum testis called rete testis, which subsequently drains into the epididymis through 10-15 efferent ducts * Efferent ducts in head of epididymis (globus major) unite to form a single duct (globus minor) in body and tail region, which continues as the vas deferens. * Mediastinum testis: thickened area of tunica albuginea where ducts, nerves, and vessels enter and exit testis Blood supply The testes are supplied by testicular arteries, arising from the aorta, just below the origin of renal arteries. It runs in the spermatic cord, gives off a branch to the epididymis and reaches the back of the testis and divide into medial and lateral branches. The branches sweep around within the tuniaca albuginea and penestrate the substance of hte organ. Anastomosis occur between the testicular, cremasteric and ductal arteries but not enough blood supply if testicular artery is cut off. Venous drainage It is a paired vein, with one supplying each testis: * the right testicular vein generally joins the inferior vena cava; * the left testicular vein, unlike the right one, joins the left renal vein instead of the inferior vena cava. The veins emerge from the back of the testis, and receive tributaries from the epididymis; they unite and form a convoluted plexus, called the pampiniform plexus, which constitutes a large proportion of the spermatic cord. These ascend along the cord, in front of the ductus deferens. Below the subcutaneous inguinal ring, they unite to form three or four veins, which pass along the inguinal canal, and, entering the abdomen through the abdominal inguinal ring, coalesce to form two veins, which ascend on the Psoas major, behind the peritoneum, lying one on either side of the internal spermatic artery. These unite to form a single vein, which opens, on the right side, into the inferior vena cava (at an acute angle), on the left side into the left renal vein (at a right angle). Since the left testicular vein pass to the left renal vein before it empties, this results in a higher prevalence of left testicle varicocele because gravity effect on the vein. Moreover, the left renal vein passes between the abdominal aorta and the superior mesenteric artery and is often compressed by an enlarged superior mesenteric artery—this is called the "Nutcracker effect" Nerve supply Testes receives autonomic (sympathetic) innervation from the spermatic plexus, originating from the para-aortic ganglia. Lymphatic supply Lymphatic drainage of testes is through lymphatics running with the testicular arteries, draining into para-aortic lymph nodes. Variant anatomy * polyorchidism (very rare): ** bilobed testes: thought to be a variant of polyorchidism * testicular appendages: may arise from the testes and have a variable incidence Epididymis is''' '''a firm structure attached behind the testis with the vas deferens to its medial side. it consists of highly coiled tube packed together by fibrous tissue. * The body is separated from the testis by a recess called the sinus of epididymis. * Efferent ductules form head (globus major) ** Unite to form single, long, highly convoluted tubule in body of epididymis * Tubule continues inferiorly to form epididymal tail (globus minor) ** Attached to lower pole of testis by loose areolar tissue * Tubule emerges at acute angle from tail as vas deferens (also know as ductus deferens) ** Continues cephalad within spermatic cord ** Eventually merges with duct of seminal vesicle to form ejaculatory duct